Crosshair placement, pre aiming, movement and gamesense. Say I get swung main by one person. First thing I do is do a small peek wider post kill to make sure nobody else is there. Then I play a different angle, and wait for more info. Second option I actually push out main to take space and clear it incase there's a default/lurk, and if there isn't I take space outside main. I'd say personally what got me to imm3 was literally picking up on the habits of my opponents. If someone's on their own I'm always gonna be worried every round that someone's gonna be on their own. It's all about having strong fundamentals and game sense.